The present invention relates to devices for ground compaction, which are formed as roller vehicles.
Devices of the above mentioned general type are known in the art. Conventional devices for ground compaction are formed so that they exclusively perform compaction of the ground. However such roller vehicles can not provide levelling of unevenness of the ground. For this purpose, additional levelling vehicles are needed to eliminate the ground unevenness before the compaction.
Accordingly, it is an object of present invention to provide a roller vehicle for ground compaction which eliminates the disadvantages of the prior art.
More particularly, it is an object of present invention to provide a roller vehicle for ground compaction which is designed so that for levelling and compaction of the ground no longer two separate vehicles must be provided.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a roller vehicle which has means for ground compaction, such as for example a trench roller, and additionally is provided with a levelling device.
When the roller vehicle is designed in accordance with the present invention, the same vehicle can be efficiently used to perform both levelling and compaction of the ground. As a result, the whole process of levelling and compaction can be performed in a shorter time and with lower expenses.
In accordance with a preferable embodiment of the invention, the levelling device of the inventive roller vehicle is formed as a blade.
The levelling device can be movable up and down, for easy maneuvering of the roller vehicle. Moreover, any desirable level of the ground surface can be planned.
In accordance with a further embodiment, the levelling device is movable up and down by means of a lifting device. Therefore the displaced ground can not hindered the levelling device during lifting.
The lifting device in accordance with the present invention can be formed in a structurally especially simple manner, when it includes a telescopable extensible and retractable cylinder unit. The cylinder unit can be driven for example from the available hydraulic system.
When the lifting device lifts the levelling device inclinedly upwardly relative to the vehicle, the levelling unit despite the displaced ground is lifted without a high resistance, since then it is moved back to the vehicle from the displaced ground.
When the levelling device is turned to a horizontal, in particular around its central point, the surface to be leveled can be leveled at any desirable angle to the horizontal.
The levelling device can be mounted on an upper part of the vehicle which is vibrationally uncoupled from the ground compacting part. In this manner, the levelling device is protected from vibrations which result from shaking of the ground compacting part. Therefore damages to the levelling device are avoided.
It is advantageous when in accordance with the present invention, the same hydraulic oil, with which the circuit for producing the vibrations of the compacting part, is used in the circuit for lifting and lowering of the levelling device. For this purpose only one valve is needed, to direct the hydraulic oil in a respective one of the circuits.
The upper part of the compacting part can be clamped so as to prevent that the upper part connected with the levelling device, when the levelling device is oriented inclinedly to a horizontal, is also inclined because of the reaction forces. This can be achieved in an especially simple way by hydraulically operating clamping cylinder.
When desired, the levelling device can be controlled manually and/or remotely. Remote control can be performed for example by radio or infrared light.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.